1. Field of the invention
This invention relates, generally, to bailers. More particularly, it relates to means and methods for inhibiting contamination by oxygen of a sample when emptying a bailer.
2. Description of the Prior Art
There are two commonly used methods for emptying a bailer.
In a first method, the bailer is maintained in an upright configuration in a substantially vertical plane, i.e., with the leading end or bottom of the bailer positioned directly below the trailing end or top thereof. A device known in the industry as a VOC device is positioned at the bottom of the bailer and manually lifted so that it lifts a check ball at the leading end of the bailer from its seat, thereby allowing the liquid fluid within the bailer to flow out. The liquid fluid exits the bailer and flows through an external filter to remove sand, mud, and the like. The filtered sample is collected into a container that is sent to a laboratory for analysis.
In a second method, the bailer is decanted from its open upper end, just as a glass of water may be emptied. The bailer is tilted from the vertical and gradually is inverted so that the entire sample flows therefrom. As in the VOC method, the decanted fluid is filtered and collected into a container.
Both methods have been used for many years but both have their shortcomings.
The first method is the more expensive method of the two, because it requires purchase of a VOC device for each sample taken. Since the sample contacts the VOC device as the sample flows from the bailer, the VOC device must be maintained in a sterile condition until used and it must be discarded or cleaned and recycled after each use to avoid cross contamination between samples. Moreover, since the user must hold the VOC device, there are times when the liquid fluid flowing from the bailer will contact the user""s hands. This contaminates the sample and may injure the user if the sample is highly acidic or caustic.
Perhaps the most important shortcoming, however, is the contamination of the sample by oxygen in the atmosphere when the VOC device is used. When the VOC device lifts the check ball from its seat, air flows into the bailer from its leading, lower end and bubbles up to the surface of the sample at the top of the bailer. This flow of bubbles continues until the bailer has been emptied. The bubbles are large in size and number and introduce a considerable, easily visible turbulence into the sample as it flows from the bailer. Therefore, oxygen from the ambient atmosphere is mixed with the sample, thereby contaminating it.
The decanting method is less expensive since it requires no VOC device, and is safer because it is less likely to cause sample to contact a user""s hand. However, the sample is also contaminated by contact with oxygen in the atmosphere as it is decanted. The amount of contamination is believed to be less than the contamination caused by the turbulent upward flow of bubbles introduced by use of a VOC device, but the contamination is still so significant that some environmental regulations call for the use of pumps to collect water from wells, to the exclusion of bailers.
Since pumps costs thousands of dollars per pump and bailers just a few dollars per bailer, the public is better served by the use of inexpensive bailers. Although a bailer cannot be reused, a pump must also be cleaned when it is moved from one well to another, and the cost of such cleaning far exceeds the cost of a bailer. The plastic from which a bailer is formed is also recyclable, further reducing the ultimate cost of a bailer.
What is needed, then, is a means for emptying a bailer that minimizes oxygen contamination as the bailer is emptied.
Environmental regulation agencies often require that liquid fluid be collected from a well or other body of water at a predetermined depth. However, known bailers have only one check valve, at the lower end thereof. Thus, when the bailer is raised from the body of liquid fluid, the liquid fluid in the bailer is free to flow out the top thereof, being replaced by liquid fluid near the surface of the body of water.
Thus there is a need for a bailer construction that can bring to the surface an amount of liquid fluid collected at a predetermined depth.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled.
The long-standing but heretofore unfulfilled needs are now met by a new, useful, and nonobvious bailer that includes a cylindrical main body having a hollow interior adapted to hold a predetermined quantity of liquid fluid. A first check valve means is connected to a leading end of the bailer and a second check valve means is disposed in spaced relation to the first check valve means in the hollow interior near a trailing end of the bailer. A column of liquid fluid is captured within the hollow interior when the bailer is lowered into a body of liquid fluid. The column has a height equal to the spacing between the first and second check valve means. The column of liquid fluid is collected by inserting the bailer to a predetermined depth in the body of liquid fluid and retracting the bailer therefrom.
In a second embodiment, a vent opening is formed in the cylindrical main body at a preselected point between the first and second check valve means. The vent opening is preferably positioned in close proximity to the second check valve means on a leading side thereof. The vent opening enables the liquid fluid to flow from the hollow interior when the first check valve is unseated, in the absence of oxygen introduction from the leading end of the bailer.
In a third embodiment, a flat is formed in a cylindrical wall that forms a part of the second check valve means and a vent opening is formed in the cylindrical wall in radial juxtaposition to the flat. The vent opening substantially prevents oxygen contamination of the liquid fluid as the liquid fluid flows from the leading end of the bailer.
An important object is to provide a bailer that can collect samples of liquid fluid at a preselected depth.
Another important object of this invention is to provide a method for emptying a bailer that minimizes oxygen contamination of the sample.
These and other important objects, advantages, and features of the invention will become clear as this description proceeds.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims.